-
[show abstract]
[hide abstract]
ABSTRACT: To investigate the influence of tilt and decentration of scleral-sutured intraocular lenses (IOLs) on ocular higher-order wavefront aberrations.
In 45 eyes of 36 patients who had undergone scleral suture fixation of posterior chamber IOL, tilt and decentration of IOLs were determined by Scheimpflug videophotography, and higher-order aberration for a 4-mm pupil was measured using the Hartmann-Shack aberrometer. In another 100 eyes of 100 patients after standard cataract surgery with posterior chamber IOL implantation, ocular higher-order aberration was measured.
In eyes with scleral-sutured IOL, the mean (SD) tilt angle and decentration were 4.43 degrees (3.02 degrees ) and 0.279 (0.162) mm, respectively. Ocular coma-like aberration in the sutured IOL group was 0.324 (0.170) microm, which was significantly greater than that of the standard cataract surgery group (0.169 (0.061) microm, p<0.001, Student's t test). No significant difference was found in ocular spherical-like aberration between the sutured IOL group (0.142 (0.065) microm) and standard surgery group (0.126 (0.033) microm; p = 0.254). In the sutured IOL group, IOL tilt significantly correlated with ocular coma-like aberration (Pearson's correlation coefficient r = 0.628, p<0.001), but no significant correlation was found between IOL tilt and ocular spherical-like aberration (r = 0.222, p = 0.175). The IOL tilt did not correlate with corneal coma-like (r = 0.289, p = 0.171) and spherical-like (r = 0.150, p = 0.356) aberrations. The IOL decentration did not correlate with any higher-order aberrations.
In eyes with scleral-sutured posterior chamber IOL, tilting of the lens induces considerable amount of ocular coma-like aberrations.
British Journal of Ophthalmology 02/2007; 91(2):185-8. · 2.90 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To compare the postoperative performance of single and three piece acrylic foldable intraocular lenses (IOLs).
20 patients underwent bilateral cataract surgery with a single piece SA30AL IOL in one eye and a three piece MA30BA IOL in the other eye. The eyes were randomly assigned to either a single or three piece lens. The amount of IOL decentration and tilt, area of anterior capsule opening, and degree of posterior capsule opacification were measured using the Scheimpflug anterior segment analysis system (Nidek EAS-1000). Visual acuity and contrast sensitivity were examined. Measurements were performed by masked examiners before and 1 day, 1 week, 1, 3, 6, and 18 months after surgery.
There were no significant differences between the two groups (p>0.05, paired t test) in the amount of IOL decentration, IOL tilt, area of anterior capsule opening, degree of posterior capsule opacification, best corrected visual acuity, and contrast sensitivity throughout the 18 month follow up period.
The single and three piece acrylic foldable IOLs are equally stable in the eye after surgery.
British Journal of Ophthalmology 07/2004; 88(6):746-9. · 2.90 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To compare central corneal thickness measurements of three pachymetry devices in eyes after laser in situ keratomileusis (LASIK).
Central corneal thickness was measured in 203 eyes after myopic LASIK. Orbscan II scanning slit topography (Bausch & Lomb), SP-2000P non-contact specular microscopy (Topcon), and ultrasonic pachymetry (Tomey) were used in this sequence.
Three devices gave significantly different corneal thickness readings (p<0.0001, repeated measure analysis of variance). The measurements of Orbscan II (445.6 (SD 60.0) microm) were significantly smaller than those of noncontact specular microscopy (467.9 (SD 40.2) micro m; p<0.0001, Tukey multiple comparison) and ultrasonic pachymetry (478.8 (SD 41.9) microm; p<0.0001). The value obtained with SP-2000P non-contact specular microscopy was significantly smaller than that taken with ultrasonic pachymetry (p<0.001). There were significant linear correlations between scanning slit topography and non-contact specular microscopy (Pearson's correlation coefficient r = 0.912, p<0.0001), non-contact specular microscopy and ultrasonic pachymetry (r = 0.968, p<0.0001), and ultrasonic pachymetry and scanning slit topography (r = 0.933, p<0.0001).
In post-LASIK eyes, Orbscan II scanning slit topography significantly underestimated corneal thickness. Non-contact specular microscopy gave smaller thickness readings than ultrasonic pachymetry, but these two units showed an excellent linear correlation.
British Journal of Ophthalmology 04/2004; 88(4):466-8. · 2.90 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To evaluate prospectively the corneal refractive status before and after pterygium surgery and its relationship with preoperative pterygium size.
Prospective, nonrandomized, comparative (self-controlled) trial.
One hundred thirty-six eyes undergoing primary pterygium removal surgery.
Corneal spherical power, astigmatism, surface regularity index (SRI), and surface asymmetry index (SAI) before and after surgery, and the preoperative pterygium size.
Before surgery, pterygium size significantly correlated with spherical power (Pearson's correlation coefficient, r = -0.370, P < 0.001), astigmatism (r = 0.600, P < 0.001), SRI (r = 0.367, P < 0.001), and SAI (r = 0.387, P < 0.001). The surgery significantly increased spherical power of the cornea, whereas astigmatism, SRI, and SAI were significantly decreased by the surgery (P < 0.01, paired t test with Bonferroni's correction of P value for multiple comparison). Surgically induced changes in spherical power (r = 0.598, P < 0.001) and astigmatism (r = 0.653, P < 0.001) significantly correlated with the preoperative pterygium size. Precise prediction of the magnitude of refractive changes based on the preoperative pterygium size was difficult.
The presence of pterygium and its removal significantly influence the corneal refraction including spherical power, astigmatism, asymmetry, and irregularity, with the larger pterygium exerting the greater influence.
Ophthalmology 09/2000; 107(8):1568-71. · 5.45 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To investigate the influence of excimer laser photorefractive keratectomy on the refraction and geometry of the posterior corneal surface.
Miyata Eye Hospital, Miyazaki, Japan.
Thirty-seven eyes of 21 patients with refractive errors of -2.00 to -9.75 diopters (D) were treated with the VISX Twenty-Twenty excimer laser system. The refractive and anteroposterior changes in the posterior corneal surface were measured using scanning-slit corneal topography (Orbscan, Orbtek, Inc.) preoperatively and 1 week and 1 and 3 months postoperatively.
Mean posterior corneal refraction was -6.51 D +/- 0. 29 (SD) preoperatively; it decreased to -7.00 +/- 0.49 D, -7.00 +/- 0.55 D, and -6.92 +/- 0.42 D at 1 week, 1 month, and 3 months, respectively (P <.001, Tukey multiple comparison). Mean forward shift of the posterior corneal surface was 29.5 +/- 1.9 microm, 34.4 +/- 3.4 microm, and 54.3 +/- 4.0 microm at 1 week, 1 month, and 3 months, respectively. The amount of posterior corneal refractive change correlated with the degree of forward shift (r= -0.691, P <. 001). The residual corneal thickness correlated with the refractive change (r = 0.524, P <.001) and the forward shift (r = -0.851, P <. 001) of the posterior corneal surface.
Photorefractive keratectomy induced significant refractive changes in the posterior corneal surface and forward shift of the cornea, both of which correlated with the thinness of the residual cornea.
Journal of Cataract [?] Refractive Surgery 07/2000; 26(6):867-71. · 2.26 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To assess quantitatively corneal irregular astigmatism in association with best spectacle-corrected visual acuity.
Refractive powers on a mire ring measured with computerized videokeratography were decomposed, using the Fourier series harmonic analysis. Extracting spherical and regular astigmatic components, the remaining irregular astigmatic component was quantified on rings 2 through 9. A weighted average was calculated by using the Stiles-Crawford effect on the basis of the radius of each ring of each eye and was used as an index of the irregular astigmatic component. Data analyses were carried out in 108 eyes, including 53 normal eyes, 34 eyes with keratoconus, and 21 eyes that had undergone penetrating keratoplasty for keratoconus. Keratoconic eyes and eyes after keratoplasty were included in the study only if visual acuity, corrected with a hard contact lens, was 20/20 or better. Logarithm of best spectacle-corrected visual acuity, age, type of disease, refractive astigmatism, irregular astigmatic component, surface regularity index, and surface asymmetry index were analyzed.
In results of multiple regression analysis, the irregular astigmatic component was significantly correlated with best spectacle-corrected visual acuity (r = -0.744; adjusted R2 = 0.549; P < 0.001), whereas other explanatory variables showed no correlation with best spectacle-corrected visual acuity.
This model of the irregular astigmatic component seems to be an efficient, quantitative means of describing corneal irregular astigmatism.
Investigative Ophthalmology & Visual Science 04/1998; 39(5):705-9. · 3.60 Impact Factor
